360 
MARSHALL: ADDITIONS TO ‘ BRITISH CONCHOLOGY.” 
subquadrate, and do not always lose this contour ; these 
are analogous to Cyfrina tslandica var. crasstor. In Jef- 
frey’s generic plate the right and left valves are odd ones ; 
one represents the subquadrate form, and the other the 
typical one. 
Dr. Jeffreys always and persistently affirmed that the 
fry of this species is what is generally known as Ked/ze//a 
abysstcola Sars, but most conchologists differ from him on 
that point. It occurs in such profusion in some of the 
Norwegian fjords as should make the adult common on 
the same ground, even as dead valves, whereas it is not 
so ; and while thousands of Ke//ie//a may be taken up to a 
line in diameter, azd no /arger, an adult one cannot be 
found. Per contra, in the British seas, numbers of 
Isocardia may be dredged or procured from the trawlers, 
yet the fry (or Ke//iel/a) are never found ; they are un- 
known to me from ordinary dredgings in British waters, 
although they have been taken in deep water off our 
coasts by the ‘ Lightning’ and ‘ Porcupine.’ It would be 
remarkable, therefore, if, as alleged, we find adult /socardia 
abundant in England, but not the fry, while in Norway 
and elsewhere the alleged fry are in swarms, and the adult 
absent. Now, it appears that some time ago I detected 
among some small shells what I consider to be a veritable 
baby Zsocardia, which was dredged in the Hebrides in 24 
fathoms. It is less than a line in length and breadth, and 
looks exactly what one should expect to grow into an adult 
Tsocardia. tis not unlike a Crenella rhombea of the same 
size in outline, is thin and gibbous ; the beaks are already 
slightly incurved, and the teeth are identically the same as 
in the adult. The colour, instead of being pearl-white and 
semi-transparent, as in Ke//e//a, is dirty-white and opaque, ° 
with frosted markings. Its whole appearance is convincing 
as being a very juvenile Zsocardia. Sars has described the 
animal of Ked/ieldz, and pointed out marked differences 
J.C., vili., Apr. 18y7. 
